The invention relates to a process which enables maintenance of proper weld quality in the course of a welding operation by calling the attention of the worker to the failure prior to occurring. Furtheron, the process is well suited for marking the failure spots on the workpiece and by recording continuously input signals and processed signals (failure signals) for the demonstration of quality.
In the course of producing steel structures quality of the welding fastening the single elements of the structure to each other ultimately determines the quality of said structures, accordingly, a considerable part of productional costs are alloted to welding and testing thereof. In addition to high costs, this fact fundamentally influences transit time, since only few welders are able to produce faultless welds being in compliance with the high qualitative demands. Costs and transit time are further increased by the necessity that for the sake of product control welds are to be subjected to an X-ray examination and after having corrected the faults, inspection with a repeated X-ray examination is also imperative. Correction, however, may result in damages in the basic material causing premature failure of the structures i.e. reduction of loadability.
Up to now it has been attempted to eliminate said problems so that are welding apparatuses have been set as optimal as possible and, provided with means regulating the process during operation. This method proved unsuccessful, in particular, under adverse circumstances.
In the patent No. HU 164 536 a process for the setting of welding apparatuses is described. This patent starts from the conception that melting of the welding electrodes and, accordingly the welding properties, are fundamentally determined by the electric parameters of the welding process (welding voltage and arc current, relative period of short-circuiting and drop frequency, both to be calculated therefrom).
By measuring the arc current and voltage the welding parameters of a given task can be determined, thereafter, by changing inductive resistance of the welding apparatus optimal values of the velocity of changing current are adjusted. The welder performs his work with this optimally set apparatus.
According to the patent U.S. Pat. No. 4,103,141 it is not sufficient to set the welding apparatus prior to beginning the welding process only once, but it has to be regulated continuously during the process in order to keep the values of arc voltage and arc current within a predetermined range, whereby welding of proper quality can be obtained.
An equipment is also known which controls the welder himself while working.
Such an equipment is disclosed in the patent U.S. Pat. No. 4,063,075. This solution functions by means of measuring stations having been installed on single working places where a centrally located computer controls and records the activity of single workers (maximally for 100 working places). The computer registers the number of arc ignitions, duration of continuous welding, the parameters and consumed electric energy.
The previously described patents examine but the process of welding and did not yield a satisfactory solution; in the course of practice experience could be gained, and even with optimally adjusted and controlling (semi-automatic) apparatuses only well qualified welders are able to make a faultless weld and even in this case qualification can be negatively influenced by tiredness, inattention, bad conditions etc., as a consequence control X-ray examinations of a considerable number cannot be omitted.
The known apparatus controlling the welders themselves did not yield the solution needed either, as it controls the power and efficiency of the worker and his discipline of labour but qualitative welds are not at all assured.
Experiences having been gained in the course of long years of practice unambiguously show that weld quality primarily depends on the welder himself and only secondarly on the apparatus used, as improper function of the apparatus or smaller errors of adjusting can be equalized by the knowledge, experience and manual skill of the welder, at the same time, if these qualifications are missing even with the optimally adjusted apparatus weld faults will occur.
Welders perform fundamental welding phases using a plurality of individual methods, e.g. with different handpositions, all influencing the result of the welding and quality of welding. Analysing the work of welders, a general working method can be determined, representing the working system of highly qualified welders.